NAME

       vga_setmode - sets a video mode

SYNOPSIS

       #include <vga.h>

       int vga_setmode(int mode);

DESCRIPTION

       vga_setmode(int  mode)  selects  the  video mode given and clears the screen (if it was a graphics mode).
       Basically this should be the first action of your application after calling vga_init(3) and  finding  out
       which mode to use.  Prior to exiting your application should call vga_setmode(TEXT).

       vga_setmode() returns 0 on success and -1 if this mode is not available.

       From  svgalib-1.4.1, if mode is -1 then vga_setmode() returns the current svgalib version, in BCD format,
       so svgalib 1.4.1 returns 0x1410.

       mode should be one of the following, predefined values, or generally a  value  in  range  1  <=  mode  <=
       vga_lastmodenumber() where vga_modeinfo(3) returned details about this mode. Instead of trying to set the
       mode,  vga_hasmode(3)  determines if the mode would actually be supported. It is also possible to use the
       numeric values given below though this  is  discouraged.  They  are  commonly  used  as  values  for  the
       SVGALIB_DEFAULT_MODE environment variable to set the vga_getdefaultmode(3).

       Here are the predefined values for mode.

   Text mode
       TEXT(0)  restores  textmode and falls back to ordinary text console handling. All other calls switch to a
       graphics mode. You should set this mode prior to exiting an svgalib application.

   VGA compatible graphics modes
       In general, for all modes following, the first number is the amount of x pixels, the second the amount of
       y pixels, the third the number of colors, with shortcuts 32K,  64K,  16M,  16M4  for  32768,  65536,  and
       1677721.  Those  with  2 or more than 256 colors use fixed color mappings (either black and white or some
       RGB true/high color) the others make use of a color lookup table.

       Memory layout for the VGA modes is weird. Too weird to be explained here, but you can check the usual VGA
       literature.  vga_setmodeX(3) has a short explanation which is valid for all 256 color modes.

       G320x200x16(1),  G640x200x16(2),  G640x350x16(3),   G640x480x16(4),   G320x200x256(5),   G320x240x256(6),
       G320x400x256(7), G360x480x256(8), and G640x480x2(9)

   Basic SVGA modes
       These use linear 256 color memory layouts similar to G320x200x256.

       G640x480x256(10), G800x600x256(11), G1024x768x256(12), and G1280x1024x256(13)

   High color SVGA modes
       These  also use linear memory layouts, but for 32K & 64K each pixel occupies two bytes and three for 16M.
       For 32K, each 16 bit word is divided into 555 bit portions refering to 5 bit red, green, blue  part.  The
       most  significant  bit is ignored by the card. For 64K the division is 565 allowing to specify green in a
       little bit more detail (Human eyes are more sensitive to green. People joke this is because our ancestors
       lived in trees where light was filtered through green leaves).

       For the 16M modes, from low to high addresses the 3 bytes are named BGR and specify the blue, green,  red
       parts of the pixel value.

       G320x200x32K(14),     G320x200x64K(15),     G320x200x16M(16),     G640x480x32K(17),     G640x480x64K(18),
       G640x480x16M(19),    G800x600x32K(20),     G800x600x64K(21),     G800x600x16M(22),     G1024x768x32K(23),
       G1024x768x64K(24), G1024x768x16M(25), G1280x1024x32K(26), G1280x1024x64K(27), and G1280x1024x16M(28)

   High resolutions with less color numbers.
       Memory  layout  is  probably one nibble per pixel, two pixels per byte in a linear fashion where the most
       significant nibble is the left most pixel.

       G800x600x16(29), G1024x768x16(30), and G1280x1024x16(31)

   Hercules emulation mode
       Again check out the ordinary VGA literature for the memory layout.

       G720x348x2(32)

   32-bit per pixel modes
       These are similar to 16M but each pixel uses four bytes. The first three  are  similar  to  16M  but  the
       fourth is left empty and ignored by the VGA card (you can store own status there).

       This eases pixel address calculations on the screen and drawing operations. However, 1/3 more data has to
       be  moved  to  the  screen.  Experiments show that usually the higher memory bandwidth used outweighs the
       effects of the simplified algorithms by far.

       G320x200x16M32(33), G640x480x16M32(34), G800x600x16M32(35), G1024x768x16M32(36), and G1280x1024x16M32(37)

   Some more resolutions
       It should by now be clear how the modes will look.

       G1152x864x16(38),    G1152x864x256(39),    G1152x864x32K(40),    G1152x864x64K(41),    G1152x864x16M(42),
       G1152x864x16M32(43),   G1600x1200x16(44),   G1600x1200x256(45),  G1600x1200x32K(46),  G1600x1200x64K(47),
       G1600x1200x16M(48), and G1600x1200x16M32(49)

       The vgatest(6) produces a list of supported modes for your hardware, prints some info on  the  modes  and
       allows you to try each of them.

SEE ALSO

       svgalib(7),   vgagl(7),   libvga.config(5),  vgatest(6),  vga_hasmode(3),  vga_init(3),  vga_modeinfo(3),
       vga_getcurrentmode(3),      vga_getdefaultmode(3),       vga_lastmodenumber(3),       vga_getmodename(3),
       vga_getmodenumber(3)

AUTHOR

       This  manual  page  was  edited by Michael Weller <eowmob@exp-math.uni-essen.de>. The exact source of the
       referenced function as well as of the original documentation is unknown.

       It  is  very  likely  that  both  are  at  least  to   some   extent   are   due   to   Harm   Hanemaayer
       <H.Hanemaayer@inter.nl.net>.

       Occasionally  this  might  be wrong. I hereby asked to be excused by the original author and will happily
       accept any additions or corrections to this first version of the svgalib manual.

Svgalib 1.4.1                                      28 Jul 1999                                    vga_setmode(3)